Sheet material/mailpiece handling systems frequently require sheet material, assembled/folded collations or completed mailpieces (hereinafter collectively referred to as “sheet material”) to be turned over to match a specific downstream requirement. For example, mailpiece fabrication equipment typically requires that sheet material be oriented face-up or face down depending upon the orientation of a receiving envelope. This requirement has come under increasing demand as new and old equipment have, over the course of time, been merged. That is, some mailpiece fabrication systems require a face-up orientation while others employ a face-down presentation. Additionally, it may be necessary to change the orientation of a mailpiece to accommodate a specific printing requirement, i.e., printing on a particular side of an envelope.
Various inversion modules have been developed to reorient sheet material for use in sheet handling equipment. One such apparatus is a twist module wherein sheet material is directed linearly along a spiral path typically effected by a series of twisted belts or chords. While such twist modules retain the respective leading and trailing edge position of the sheet material, such modules require a lengthy axial path to change the face-up/face-down orientation of the sheet material. Furthermore, twist modules are less reliable when handling stacked collations inasmuch as the stacked sheets tend to skew as they follow the spiral path.
Another common requirement is for the sheet material to be re-directed at a right angle from an upstream feed path to be processed along another feed path, out-sorted or stacked in a sorting bin. For example, a mailpiece inserter will frequently employ modules for re-directing the feed path to accommodate the configuration of a customers facility. Additionally, it may be desirable to re-direct completed mailpieces ninety-degrees from the primary feed path to stack or out-sort mailpieces in a bin, tray or container disposed laterally of the primary feed path.
Yet another requirement relates to the registration and conveyance of the sheet material after the sheet material has been handled or in preparation for a subsequent downstream operation. For example, sheet material will may skew during handling, e.g., as the orientation changes, and, as such, correction may be required. Commonly, such correction is effected by urging the sheet material against a shoulder or wall to register the individual sheets, or square the leading and trailing edges of a mailpiece relative to the primary feed path. This is typically achieved by a series of banked rollers arranged so as to define a shallow angle relative to the feed path and the registration wall. The shallow angle functions to impart components of velocity, i.e., to the sheet material, in two directions—a primary velocity component along the feed path and a secondary velocity component toward the registration wall.
While this arrangement is well-suited for sheet material travelling along the primary feed path, i.e., substantially parallel to the primary velocity component produced by the banked rollers, such arrangement is less effective, or entirely ineffective, should the sheet material enter at a more aggressive angle, e.g., ninety-degrees. That is, the orientation of the banked rollers can inhibit the smooth transition of the sheet material to the primary feed path.
Furthermore, inasmuch as the banked rollers drive the sheet material as a function of the friction developed by, or under the weight of, the sheet material, it can be difficult to accelerate the sheet material to the full inserter throughput speed. For example, when sheet material enters the banked rollers, the sheet material may have no initial velocity in the direction of the primary feed path. Consequently, the sheet material must be rapidly accelerated, i.e., from zero velocity to the full inserter throughput speed, to prevent upstream sheet material from interfering or colliding with the downstream material. Difficulties can arise when friction forces developed between the sheet material and banked rollers are low, and, accordingly, the banked rollers do not develop sufficient traction to adequately/rapidly accelerate the sheet material.
A need, therefore, an apparatus which satisfies a requirement to rapidly accelerate sheet material along a feed path while effecting registration of the sheet material during conveyance.
The invention will be fully understood when reference is made to the following detailed description taken in conjunction with the accompanying drawings.